Purpose To examine the associations between illness perceptions and expectations about full return to work (RTW) of workers with chronic diseases and their significant others. Methods This study used cross-sectional data of 94 dyads consisting of workers with chronic diseases and their significant others. We performed dyadic analyses based on the Actor-Partner Interdependence Model (APIM), estimating associations of illness perceptions of the two members of the dyad with their own expectations about the worker's full RTW within six months (actor effect) as well as with the other dyad member's expectations about the worker's RTW (partner effect). Results Illness perceptions of one dyad member were significantly associated with his or her own RTW expectations (actor effect composite illness perceptions score; B = -0.05, p < .001; r(d) = .37) and with the other dyad member's RTW expectations (partner effect composite illness perceptions score; B = -0.04, p < .001; r(d) = .35). That is, more negative illness perceptions of one member of the dyad were associated with more negative RTW expectations in both dyad members. For most illness perception domains, we found small to moderate actor and partner effects on RTW expectations (r(d) range: .23-.44). Conclusions This study suggests that illness perceptions and RTW expectations should be considered at a dyadic level as workers and their significant others influence each other's beliefs. When trying to facilitate adaptive illness perceptions and RTW expectations, involving significant others may be more effective than an individualistic approach targeted at the worker only.