Routine observation of stained histological preparations for the detection of Helicobacter pylori (HP) has shown a variable presence of mast cells in the mucosa of patients suffering from gastritis. Our aim was to verify whether any correlations exist between HP positivity, type of gastritis and presence of mast cells. We examined 300 bioptic fragments of gastric mucosa obtained by diagnostic oesophagogastroduodenoscopy. The study population consisted of 88 patients with chronic superficial gastritis and 12 with chronic atrophic gastritis (59 males and 41 females). HP detection was performed on Giemsa-stained preparations. Mast cell detection was performed on Giemsa- and PAS-stained preparations. Seventy percent of chronic superficial gastritis cases were found to be HP-positive and mast cells were present in 90% of these and absent in 10%. In the chronic atrophic gastritis cases 50% were HP-positive and mast cells were present in 50% and absent in the rest. HP is regarded as the causal agent of type B gastritis. On the basis of our data a significant correlation was found (86%) between HP-positivity and presence of mast cells in the inflammatory gastric mucosa.