This　paper　investigates　size　effects　on　the　mechanical　response　of　additively　manufactured　lattice　structures　based　on　a　commercially　available　polylactic　acid　(PLA)　polymer.　Initial　attention　is　focused　on　investigating　geometrical　effects　in　the　mechanical　properties　of　simple　beams　and　cubes.　Following　this,　a　number　of　geometrically　scaled　lattice　structures　based　on　the　body-centered　cubic　design　were　manufactured　and　tested　in　order　to　highlight　size　effects　in　their　compression　properties　and　failure　modes.　A　finite　element　analysis　was　also　conducted　in　order　to　compare　the　predicted　modes　of　failure　with　those　observed　experimentally.　Scaling　effects　were　observed　in　the　compression　response　of　the　PLA　cubes,　with　the　compression　strength　increasing　by　approximately　19%　over　the　range　of　scale　sizes　investigated.　Similar　size-related　effects　were　observed　in　the　flexural　samples,　where　a　brittle　mode　of　failure　was　observed　at　all　scale　sizes.　Here,　the　flexural　strength　increased　by　approximately　18%　when　passing　from　the　quarter　size　sample　to　its　full-scale　counterpart.　Significant　size　effects　were　observed　following　the　compression　tests　on　the　scaled　lattice　structures.　Here,　the　compression　strength　increased　by　approximately　60%　over　the　four　sample　sizes,　in　spite　of　the　fact　that　similar　failure　modes　were　observed　in　all　samples.　Finally,　reasonably　good　agreement　was　observed　between　the　predicted　failure　modes　and　those　observed　experimentally.　However,　the　FE　models　tended　to　over-estimate　the　mechanical　properties　of　the　lattice　structures,　probably　as　a　result　of　the　fact　that　the　models　were　assumed　to　be　defect　free.