Malaria is major public health problem in Tanzania and increasing trends have been observed in the last two decades. A significant consequence of repeated malaria infections in high transmission areas is anaemia in very young children. The control of malaria in Tanzania includes both preventive and curative strategies. On the preventive side insecticide treated bed nets (ITNs) are a promising tool. ITNs have been shown to be effective in reducing malaria morbidity and mortality in controlled trials. Large-scale implementation of the technology is currently being initiated in many African countries. We report the impact of a large social marketing programme of ITNs on malaria morbidity through a series of studies, in a population of about 55,000 people in Tanzania. The ITNs social marketing programme resulted in a rapid increase in any net ownership (from 58 to 83%) and an increase in ITNs ownership (from 10 to 61%) in children under two years of age within 2 years of implementation. As a result the overall mean haemoglobin levels increased (from 8.0 to 8.9 g/dl) in the study children during the successive surveys. The prevalence of anaemia in the study population decreased from 49% to 26%. Comparison between children with ITNs and those without nets showed that ITNs had a protective efficacy of 63% (95% CI: 38 to 77) on the prevalence of parasitaemia, and 63% (95% CI: 27 to 82) on anaemia (haemoglobin £ 8 g/dl). These results endorse the wide scale implementation of ITNs in Tanzania. ITNs can only reduce the risk of malaria dis ease but cannot eliminate it. Hence, appropriate effective treatment is required. Chloroquine is a cheap and safe antimalarial and it was until recently the first line drug of choice in the National Malaria Treatment Policy. Resistance to chloroquine has been reported with increasing frequency in Tanzania and has been linked to the increasing admissions with severe disease in hospitals. A comparative randomised, open clinical trial of chloroquine against Co-artemâ (fixed combination of Artemether + Benflumetol) an alternative new antimalarial, showed seven-day parasitological cure rates of 94% for Co-artemâ and only 35% for chloroquine. Generally, Co-artemâ showed a superior clearance rate, successfully cleared higher parasite densities and suppressed new infections over a longer period of time. Furthermore, Co-artemâ suppressed more effectively gametocytes in these children, indicating a potential benefit for reducing malaria transmission. The unacceptably high chloroquine failure rates call for an urgent review of the National Malaria Treatment Guidelines. The decision to change the first line antimalarial and the choice of a new drug depend on a number of factors that include the clinical, epidemiological and social-economical factors, as well as the health infrastructure. Considering all of these dimensions, sulphadoxinepyrimenthamine (SP) was identified as a good interim replacement for chloroquine. Further Phase IV evaluation of Co-artemâ and other combination therapy regimens are required before considering their inclusion in the national treatment policy. Much work is also needed to identify suitable compounds to be used for home management of malaria, within the national treatment guidelines. Experience gained with these studies gives a description of the different methodologies and tools that can be used to evaluate different components of the National Malaria Control Programme. For example, it was difficult to assess the impact of the ITNs programme using the case-control approach. Repeated cross-sectional assessments were found to be more suitable for assessing the impact of ITNs under programme conditions, especially on malariarelated anaemia in this area of high transmission. Specific indicators for programme evaluation may need to be identified for specific interventions. These may be different from the ones used in randomised controlled trials. The use of molecular markers for monitoring and evaluation of antimalarial intervention programmes illustrate the need to develop and validate novel tools and approaches for programme evaluation. Better malaria control is expected by combining ITNs and an effective antimalarial, especially combination therapy. The evaluation, implementation, and monitoring of all these control activities requires a partnership between researchers, policy makers, health managers, in close collaboration with other stakeholders in the public and private domain, including the beneficiaries - the community