Infants in Tanzania are particularly vulnerable to under-nutrition during transition from breastmilk (as the only source of nourishment) to solid foods. A cross-sectional study was undertaken in Kilosa district in Tanzania to determine the feeding practices and the extent of wasting, stunting, and iron-deficiency anaemia. The study was done in two stages: in the first stage, a 24-hour dietary assessment was conducted to identify the type of complementary foods given and the eating habits according to age for 378 children aged 3-23 months. In the second stage, a progressive recruitment of 309 infants aged six months was made to measure weight, length, haemoglobin (Hb) concentration, zinc protoporphyrin concentration, and malaria parasitaemia. Birth-weight, the potential contributing factor to under-nutrition and iron-deficiency anaemia, was obtained from the children's clinic cards. The 24-hour dietary assessment revealed that children consumed mainly a thin porridge prepared from maize flour as complementary food. Carbohydrates contributed most energy (on average 69%), followed by fats (18.6%) and protein (on average 12.1%). The complementary food co-vered only 15%, 20%, and 27% of the recommended iron intake for children aged 6-8, 9-11 and 12-23 months respectively. The mean Hb concentration was 9.3 +/- 1.9 g/dL, 68% of the infants were moderately anaemic (7 < or =11 g/dL), and about 11% were severely anaemic with Hb below 7 g/dL, while 21% were non-anaemic Hb (> or =11 g/dL). Equally, the mean zinc protoporphyrin concentration was 10.0 +/- 6.2 microg/g Hb, and 76% of the infants were iron-deficient (>5 microg/g Hb). The prevalence of stunting was 35%, while wasting was only 1.3%. Low birth-weight and low body mass index of mothers were the strong predictors of stunting, whereas low birth-weight and iron-deficiency were the strong predictors of anaemia. The prevalence of malaria parasitaemia was high, affecting 50% of the infants. Having malaria was the only independent predictor associated with stunting, anaemia, and iron-deficiency. There is an urgent need to improve tradi-tional complementary foods in the studied community in terms of energy density, amount of fat in the diet, and bioavailability of macro and micronutrients.