Four growth experiments and a balance study were carried out to examine the effects of different fat types (beef tallow or soyabean oil) in broiler diets based on wheat, triticale, maize or barley in response to feed enzyme supplementation. Performance parameters were recorded over 35 days. Viscosity in the ileal digesta, apparent digestibility of fat and protein at the terminal ileum were measured at day 21 of age. In addition, fat digestibility was measured at the faecal level along with apparent metabolizable energy value (AME_N) and apparent net protein utilization (NPU_a). It was found that enzyme addition to all diets improved feed to gain ratio significantly. This was most visible in triticale- and barley-based diets supplemented with tallow than in the soyabean oil-containing counterparts until 21 days of age. Effects became smaller or disappeared when the whole fattening period was considered. Significantly better performance of broilers fed soyabean oil compared with tallow-containing diets was observed over the whole fattening period. Intestinal viscosity was significantly reduced by enzyme addition to all diets. Furthermore, significantly higher intestinal viscosity was found in tallow-fed birds (triticale-, barley- or maize-based diets). Apparent protein digestibility at the terminal ileum was not affected by fat type but was improved by enzyme supplementation in wheat- and barley-based diets. Fat digestibility at both the ileal and faecal levels was significantly higher in birds fed the soyabean oil-containing diets and was significantly improved after enzyme supplementation. The enzyme effect on fat digestibility was more pronounced at the faecal level and was positively correlated to AME_N and NPU_a.