This paper analyses altmetric differences by type of access to documents. We distinguish between three types of access to the document: green OA, gold OA and non-OA. Here we report a preliminary analysis based on two journals from Physics. We use this descriptive analysis as a proof-of-concept before expanding our study to other fields and introducing more advanced statistical methods. Our results show that gold OA documents are best covered in Altmetric.com and receive higher mentions than documents with other types of access. This is especially troublesome in the case of green OA, as it reflects that altmetric indicators do promote a very specific type of access closely linked with the publishing industry (Torres-Salinas, Robinson-Garcia, & Moed, 2018). Furthermore, it has negative implications for the effectiveness of institutional policies promoting green OA through the creation of repositories and OA infrastructure. This paper does not intend to delve into the reasons behind these differences, but to be a first step. Further research will require the implementation of a large-scale study in which other types of access and documents (i.e., not published pre-prints) could be included, as well as other scientific fields covered.