The experiments were carried out on a group of 90 males of guinea pigs of 300 ± 50 g in weight. The animals were divided into 6 groups equal in numbers. 5 of them were infected per os with ca 5000 invasive eggs of Ascaris suum. The blood of both infected and control guinea pigs was controlled on 1, 2, 4, 7, and 20th day after infection. The level of total lipids (according to Swahn method), WKT (Dole titrimetric method), total cholesterol and HDL cholesterol (Błaszczyszyn method) and triglicerides (colometric method) was determined. During the invasion, the decrease in all studied indicators was observed, and was particularly apparent on 4th and 7th day after infection. Only in case of WKT and triglicerides a slight increase at initial stage of invasion was found. During larval ascariasis, as it appears, the metabolism of lipids is significantly disturbed. The changes are due to the break in liver function and, presumedly, changes in hormon secrection which are provoked by the presence of the parasite
