This study addresses the effects of message type and situation on the perceived intrusiveness of mobile advertisements. Ad intrusiveness, as conceptualized by Li et al., is introduced to the field of mobile advertising and used as dependent variable in a 2x2 within-subjects factorial study design. Two message types (informative vs. entertaining) are combined with two different situations (low vs. high level of activity). Attitude towards advertising in general and ad relevance (here: product class involvement) are further variables assessed in order to test for a hypothesized impact on mobile ad intrusiveness. A survey approach was used for data collection (n=325). Main effects were analyzed with analysis of variance. Analysis of covariance and regression analysis were applied subsequently for analyzing further effects. While message type was not found to contribute significantly to the explanation of mobile ad intrusiveness, the situation type showed a highly significant effect. Three of the four assumed relationships were found in the data. The study contributes to the body of knowledge on mobile advertising effectiveness. Empirical evidence for the effects of the situational context on mobile advertising effectiveness has been found and discussed with possible implications for marketing practice.