RESUMEN
To find out the effects of summer and winter seasons. The blood pictures of 252 healthy students were studied in the last week of June, 2006 and the last week of January, 2007. Total leucocyte, absolute neutrophil, absolute lymphocyte and red blood cell counts and hamemoglobin concentration were highly significantly [P < 0.001] higher in the summer than in the winter. Packed cell volume was also significantly [P < 0.01] higher in the summer. Mean corpuscular volume [MCV] mean corpuscular haemoglobin [MCH], mean corpuscular haemoglobin concentration [MCHC] and platelet count showed a non-significant [P > 0.05] difference between the two seasons. It is concluded that there are significant seasonal variations in the blood picture of healthy young adults